Lower extremity peripheral arterial disease (PAD) affects 10% to 15% of community dwelling men and women age 65 and older. Our work and that of others show that patients with PAD have a higher prevalence of lower extremity functional impairment and increased rates of functional decline compared to persons without PAD. The specific functional impairments documented in persons with PAD are associated with increased risks of disability, nursing home placement, hospitalization, and mortality in community-dwelling populations. Supervised exercise rehabilitation programs improve treadmill walking performance in patients with PAD. However, few PAD patients have access to supervised exercise rehabilitation programs because of costs and barriers to the travel required back and forth to the exercise facility. Consequently, few PAD patients participate in supervised exercise programs. Current clinical guidelines for management of patients with PAD indicate that there are insufficient data to support home-based walking exercise programs in persons with PAD. A definitive clinical trial is needed to determine whether an intervention designed to increase home-based walking exercise improves lower extremity functioning in patients with PAD. The primary aim of this study is to determine whether an intervention designed to increase home-based walking exercise significantly improves six-minute walk performance in men and women with PAD. Our specific aims will be tested in 200 men and women with PAD. Our intervention employs a Group Mediated Cognitive Behavioral intervention to help patients with PAD overcome identified barriers and develop the skills necessary to engage in regular home walking exercise. A multidisciplinary team with internationally-recognized expertise in exercise, behavioral interventions, PAD, functional outcomes, and exercise rehabilitation has been assembled to carry out the proposed study. If a home-based walking exercise program significantly benefits patients with PAD, this finding will have significant implications for maintaining functioning and preventing functional decline in the large and growing number of men and women with PAD. Previous study shows that patients with lower extremity peripheral arterial disease (PAD) have greater functional impairment, increased rates of functional decline, and increased mobility loss compared to persons without PAD. Yet few therapies have been identified that improve lower extremity functioning or prevent functional decline or mobility loss in persons with PAD. Current clinical guidelines for management of patients with PAD indicate that there are insufficient data to support home-based walking exercise programs in persons with PAD. A definitive clinical trial is needed to determine whether an intervention designed to increase home-based walking exercise improves lower extremity functioning in patients with PAD. If a home-based walking exercise program significantly benefits patients with PAD, this finding will have significant implications for maintaining functioning and preventing functional decline in the large and growing number of men and women with PAD.